Transmission power control method and apparatus for mobile communication system

ABSTRACT

A method and apparatus for controlling the power of a signal transmitted between a base station and a mobile terminal which constitute a mobile communication system. At least one of the base station and the mobile terminal has functions to compare a predetermined reference value and a necessary transmission power obtained as a result of transmission power control in order to compensate for a signal intensity fluctuation occurring on a link between the base station and the mobile terminal, temporarily stopping the transmission if the necessary transmission power is larger than a predetermined permissible value, and transmit the signal if the necessary transmission power is equal to or smaller than the predetermined permissible value.

This is a continuation of application Ser. No. 10/376,310, filed Mar. 3,2003 (now U.S. Pat. No. 7,120,457), which, in turn, is a continuation ofU.S. application Ser. No. 09/729,272, filed Dec. 5, 2000 (now U.S. Pat.No. 6,546,260), and which, in turn, is a continuation of Ser. No.08/975,672, filed Nov. 28, 1997 (now U.S. Pat. No. 6,175,744); and theentire disclosures of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to a transmission power controlmethod and apparatus for mobile communication system which controls thetransmission power between the base station and mobile terminal of amobile communication system, and particularly to the effectivetechnology suitable for use in the transmission power control method andapparatus for mobile communication system which controls thetransmission power in accordance with the change of signals receivedbetween the base station and mobile terminal of the mobile communicationsystem of TDD-SS (Time Division Duplex-Spread Spectrum) and FDD(Frequency Division Duplex) system.

There is a conventional mobile communication system for transmitting andreceiving data by radio between base stations and mobile terminals. Thismobile communication system employs different carrier frequencies forthe up link on which signals are transmitted from a mobile terminal tothe base station and for the down link on which signals are transmittedfrom the base station to the mobile terminal by the FDD.

The signal transmitted and received between the base station and mobileterminal of this mobile communication system is attenuated along thedistance between the base station and mobile terminal, and by obstaclespresent therebetween, and fluctuated by the fading due to theinterference between the direct wave and the reflected wave, or thelike.

In order to compensate the fluctuation due to the fading in the signaltransmitted and received between the base station and the mobileterminal is dependent upon the carrier frequency, the transmission powerin the FDD mobile communication system is controlled by closed-loopcontrol. For example, the IS-95 specifications apply up linktransmission power control of the FDD system which controls thetransmission power of the terminal. The technique on the scheme of theFDD down link power control is proposed in U.S. Pat. No. 5,559,790entitled “Spread Spectrum Communication System and Transmission PowerControl Method Therefor” invented by Yano, et al., assigned to thepresent assignee and issued Sep. 24, 1996. In addition, anothertechnique on the information of the up link power control is proposed ina copending U.S. patent application Ser. No. 08/690,819 entitled “CDMAMobile Communication System and Communication Method” by thoseinventors, assigned to the present assignee and filed on Aug. 1, 1996.The disclosure of the above U.S. Application, and the continuationapplication, Ser. No. 08/678,656 of the above U.S. Patent, filed on Jul.11, 1996, are incorporated in the disclosure of this application byreference.

Whether the mobile communication system is of DMA-FDD or CDMA-TDD, thefollowing problem is caused hen transmission power control is performedthrough the transmission path between the mobile terminal and the basestation. In other words, when the attenuation of data in thetransmission path between the base station and a particular mobileterminal is temporarily increased, the base station transmits signalswith an extremely higher power in accordance with the transmission powercontrol, and thus interferes with other mobile terminals. In addition,when the transmission power from a mobile terminal, on the contrary, isexcessively risen, it also obstructs or interferes with other basestations.

Moreover, in the FDD mobile communication system, since the closed loopcontrol is still performed in which the transmission power on the uplink is controlled by the mobile terminal in accordance with the up linkpower control information obtained at the base station, while that onthe down link is controlled by the base station in accordance with thedown link power control information attained at the mobile terminal,there is the problem that it takes a long time to control thetransmission power.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a transmissionpower control method and apparatus for the mobile communication system,by which the transmission power can be prevented from being wasted andfrom obstructing other stations.

It is another object of the invention to provide a transmission powercontrol method and apparatus for the mobile communication system, whichcan fast compensate for the signal fluctuation occurring on the up linkthat is provided from the mobile terminal to the base station.

It is still another object of the invention to provide a transmissionpower control method and apparatus for the mobile communication system,which can fast compensate for the signal fluctuation caused on the downlink that is provided from the base station to the mobile terminal.

According to the concept of the present invention, there is provided atransmission power control method and apparatus for controlling thepower of a signal transmitted between a base station and a mobileterminal, which includes: means for detecting a signal fluctuationoccurring on a down link or up link; means for generating power controlinformation in order to compensate for the signal fluctuation occurringon the up link or down link on the basis of the detected signalfluctuation; means for compensating for the power of the signaltransmitted on the up link or down link on the basis of the information;and means for comparing the generated power control information and apredetermined permissible compensated value, temporarily stopping thetransmission if the power control information is larger than apredetermined permissible compensation value as a result of thecomparison, and compensating for the transmission power if the powercontrol information is equal to or smaller than the predeterminedpermissible compensation value, all the above means being provided inthe base station or mobile terminal. The above idea is usefulparticularly when a signal of data packets is transmitted between thebase station and the mobile terminal. In this idea, unlike the speechservice, when the transmission power of the packet is requested to bemore than a predetermined value, and when it will be too intense tointerfere with other base stations or mobile terminals in a mobilecommunication system, the transmission is temporarily stopped, and acertain time later it resumes, in which case it has been confirmed bythe inventors that the communications are not disturbed at all.

In order to achieve the above objects, the present invention proposesthe following typical aspects.

(1) A transmission power control method for controlling the power of asignal transmitted between the base station and the mobile terminalwhich constitute a mobile communication system, comprises the steps ofdetecting a signal fluctuation occurring on a down link that is providedto transmit a signal from the base station to the mobile terminal,generating power control information for compensating for a signalfluctuation on an up link on the basis of the detected signalfluctuation, compensating for the transmission power of the signaltransmitted on the up link from the mobile terminal to the base stationon the basis of the generated power control information, andtransmitting the power control information used for compensating for thetransmission power, and transmitting the signal of which the power hasbeen compensated, from the mobile terminal to the base station.

In the transmission power control method for the mobile communicationsystem, the mobile terminal that communicates with the base stationreceives a signal transmitted on a down link from the base station tothe mobile terminal, for example, a pilot signal transmitted on a pilotchannel.

Then, the mobile terminal detects a signal fluctuation, such as theattenuation, occurring on the down link due to the fading and distanceor an obstacle along the channel.

The mobile terminal assumes that the detected signal fluctuation in thedown link similarly occurs in the up link on which a signal istransmitted from the mobile terminal to the base station, and generatespower control information to compensate for the signal fluctuationoccurring on the up link.

Then, the mobile terminal modifies the transmission power of the signalto be transmitted on the up link from the mobile terminal to the basestation on the basis of the generated power control information.

In addition, the mobile terminal also transmits the power controlinformation used for compensating for the transmission power from themobile terminal to the base station.

Thus, according to the transmission power control method for the mobilecommunication system, since the mobile terminal compensates for thesignal fluctuation occurring on the up link for the transmission fromthe mobile terminal to the base station by detecting the signalfluctuation occurring on the down link for the transmission from thebase station to the mobile terminal, it is possible to fast compensatefor the signal fluctuation occurring on the up link for the transmissionfrom the mobile terminal to the base station.

(2) A transmission power control method for the mobile communicationsystem, according to the aspect (1), wherein the base terminal thatcommunicates with the mobile terminal has functions to receive the powercontrol information transmitted from the mobile terminal to the basestation, detect a signal fluctuation occurring on the up link for thetransmission from the mobile terminal to the base station, generatepower control information to compensate for the signal fluctuationoccurring on the down link on the basis of the detected signalfluctuation and the power control information sent from the mobileterminal, and compensate for the transmission power of the signal to betransmitted on the down link from the base station to the mobileterminal on the basis of the generated power control information.

The base station receives a signal sent on the up link from the mobileterminal to the base station, for example, a signal of reservationpackets and data packets transmitted on a reservation channel andtransmission channel.

The base station detects the signal fluctuation occurring on the up linkfor the transmission from the mobile terminal to the base station, andgenerate power control information to compensate for the signalfluctuation occurring on the down link on the basis of the detectedsignal fluctuation and the power control information sent from themobile terminal.

Then, the base station modifies the transmission power of the signaltransmitted on the down link from the base station to the mobileterminal on the basis of the generated power control information.

Thus, according to the transmission power control method for the mobilecommunication system, since the base station detects the signalfluctuation occurring on the up link for the transmission from themobile terminal to the base station, and compensates for the signalfluctuation occurring on the down link for the transmission from thebase station to the mobile terminal, it is possible to fast compensatefor the signal fluctuation occurring on the down link for thetransmission from the base station to the mobile terminal.

(3) A transmission power control method for the mobile communicationsystem, according to the aspect (1) or (2), further comprising the stepsof comparing the generated power control information and a maximumpermissible modification or compensation value, temporarily stopping thetransmission if the generated power control information is larger thanthe maximum permissible compensation value, and compensating for thetransmission power if the generated power control information is equalto or smaller than the maximum permissible compensation value.

More specifically, the base station or the mobile terminal compares thegenerated associated power control information and the maximumpermissible compensation value of the base station or the mobileterminal, temporarily stops the transmission if the generated powercontrol information is larger than the maximum permissible compensationvalue until the next time slot comes.

If the generated power control information is equal to or smaller thanthe maximum permissible compensation value, the transmission power iscompensated on the basis of the generated power control information.

Thus, according to the transmission power control method for the mobilecommunication system, since the transmission is temporarily stopped ifthe generated control information is larger than the maximum permissiblecompensation value and resumes when the power control informationbecomes equal to or smaller than the maximum permissible compensationvalue, the transmission power can be prevented from being wasted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a mobile communication system according toone embodiment of the invention.

FIG. 2 is a block diagram of a base station 100 of the mobilecommunication system according to this embodiment.

FIG. 3 is a block diagram of a mobile terminal 110 of the mobilecommunication system according to this embodiment.

FIG. 4 is a timing chart briefly showing the data transmission in themobile communication system according to this embodiment.

FIG. 5 is a flowchart showing procedures of the transmission powercontrol by the base station 100 of the mobile communication systemaccording to this embodiment.

FIG. 6 is a flowchart showing procedures of the transmission powercontrol by the mobile terminal 110 of the mobile communication systemaccording to this embodiment.

FIG. 7 is a block diagram of a mobile communication system according toanother embodiment of the invention.

FIG. 8 is a flowchart showing procedures of the transmission powercontrol by a base station 700 of a mobile communication system accordingto the above other embodiment.

FIG. 9 is a flowchart showing procedures of the transmission powercontrol by a mobile terminal 710 of a mobile communication systemaccording to the above other embodiment.

Other objects, features and advantages of the invention will becomeapparent when reading the description of the following embodiments takenin conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the transmission power control method and apparatusaccording to the invention will be described, which is used in themobile communication system and which controls the transmission powerwhen communication is made between a base station and a mobile terminalby means of the TDD-SS system.

FIG. 1 is a block diagram showing an outline of the construction of themobile communication system according to this embodiment. Referring toFIG. 1, the mobile communication system of this embodiment has the basestation 100 which includes a down link transmission power setter 101, adown link power control information comparator 102, a down link powercontrol information generator 103 and a power control informationreceiver 104, the mobile terminal 110 which includes an up linktransmission power setter 111, an up link power control informationcomparator 112, an up link power control information generator 113 and apower control information transmitter 114, communication channels 120which include an up link 121, a down link 122 and guard times 123, and acarrier frequency 124.

The base station 100 and the mobile terminal 110 are connected by the uplink 121 on which a signal is transmitted from the mobile terminal 110to the base station 100 and the down link 122 on which a signal istransmitted from the base station 100 to the mobile terminal 110. Thecommunication channels 120 on the carrier frequency 124 are assigned ina time-sharing manner to the up link 121 and down link 122 between whichthe guard times 123 are provided to prevent the interference.

The down link transmission power setter 101 of the base station 100responds to the result from the down link power control informationcomparator 102 to fix a transmission power that is to be transmitted onthe down link 122 from the base station 100.

The down link power control information comparator 102 of the basestation 100 compares whether or not the control information of down link122 which is generated by the down link power control informationgenerator 103 is larger than the maximum permissible compensation valueof the base station 100.

The down link power control information generator 103 generates powercontrol information for the down link 122 by using the signalinformation on the up link 121 and the power control information of thedown link sent from the mobile terminal 110.

Since the signal received by the base station 100 on the up link 121 hasbeen compensated by the mobile terminal 110, the down link power controlinformation generator 103 of the base station 100 computes the value ofthe signal on the up link 121 before compensation by use of the powercontrol information transmitted from the mobile terminal 110, andgenerates the power control information for the down link 122.

The power control information receiver 104 of the base station 100receives the power control information transmitted from the mobileterminal 110.

The up link transmission power setter 111 of the mobile terminal 110determines the transmission power which the mobile terminal 110 is totransmit on the up link 121 in accordance with the result from the uplink power control information comparator 112.

The up link power control information comparator 112 of the mobileterminal 110 compares whether or not the control information of the uplink 121 which is generated by the up link power control informationgenerator 113 is larger than the maximum permissible compensation valueof the mobile terminal 110.

The up link power control information generator 113 of the mobileterminal 110 generates the power control information of the up link 121by use of the signal information on the down link 122.

The power control information transmitter 114 of the mobile terminal 110transmits the power control information of the up link 121 set by the uplink transmission power setter 111 to the base station 100.

FIG. 2 is a block diagram showing an outline of the construction of thebase station 100 of the mobile communication system according to thisembodiment. The base station 100 further includes a CPU 201, a memory202, a display unit 203, an input/output unit 204, the digital signalprocessor (DSP) 205, a mobile communication exchange interface unit 206,an antenna 210, a pilot channel modulator 211, an answering channelmodulator 212, a transmission channel modulator 213, reservation channelmatched filters 214-215, transmission channel matched filters 216-217, apara-noise code generator (PN code generator) 218, adders 220 and 221,multipliers 230 and 231, and a TDD switch 240.

In the base station 100, a bus connects the CPU 201 that controls theoperation of the whole base station 100, the memory 202 that loads acontrol program for controlling the operation of the whole base station100, the display unit 203 that displays the operating condition of thebase station 100, the input/output unit 204 that instructs the basestation 100 to operate for the input/output process, the DSP 205 thatcontrols the process for communicating with the mobile terminal 110, andthe mobile communication exchange interface unit 206.

The base station 100 communicates with the mobile terminal 110 by meansof TDD-SS. Between the base station 100 and the mobile terminal 110,there are provided a pilot channel, a reservation channel, an answering(responding) channel and a transmission channel on the same carrierfrequency 124 (see FIG. 4).

The DSP 205 of the base station 100 includes the down link transmissionpower setter 101, the down link power control information comparator102, the down link power control information generator 103 and the powercontrol information receiver 104 as described above.

In addition, the DSP 205 is connected to the pilot channel modulator211, the answering channel modulator 212, the transmission channelmodulator 213, the reservation channel matched filters 214-215, thetransmission channel matched filters 216-217, the PN code generator 218,and the TDD switch 240.

The pilot channel modulator 211 of the base station 100 modulates thepilot channel for the transmission of the pilot signal, and supplies themodulated pilot signal through the adder 220, multiplier 230 and TDDswitch 240 to the antenna 210, from which it is transmitted to themobile terminal 110.

The answering channel modulator 212 modulates the answering channelthrough which an answer or response to the reservation packet receivedfrom the mobile terminal 110 is transmitted. The modulated answer to thereservation packet is supplied through the adders 220 and 221,multiplier 230 and TDD switch 240 to the antenna 210, from which it istransmitted to the mobile terminal 110.

The transmission channel modulator 213 modulates a plurality oftransmission channels on which data packets are transmitted. Themodulated data packet is supplied through the adders 220 and 221,multiplier 230 and TDD switch 240 to the antenna 210, from which it istransmitted to the mobile terminal 110.

The reservation channel matched filters 214-215 receive the reservationpackets transmitted from the mobile terminal 110, and the receivedreservation packets are processed by the DSP 205.

The transmission channel matched filters 216-217 receive the datapackets sent from the mobile terminal 110, and the received data packetsare processed by the DSP 205.

The PN code generator 218 generates the PN code that is used on each ofthe pilot channel, reservation channel, answering channel andtransmission channel.

The TDD switch 240 responds to a TDD timing signal produced from the DSP205 to timely switch the up link 121 and down link 122, or to timelychange over from transmission to reception or vice versa. When the basestation 100 receives the power control information from the mobileterminal 110, it supplies the received power control information throughthe reservation channel matched filters 214-215 and transmission channelmatched filters 216-217 to the power control information receiver 104 ofthe DSP 205.

The power control signal fixed by the down link transmission powersetter 101 of the DSP 205 is supplied to the pilot channel modulator211, answering channel modulator 212 and transmission channel modulator213

FIG. 3 shows in block diagram an outline of the construction of themobile terminal 110 of the mobile communication system according to thisembodiment. Referring to FIG. 3, the mobile terminal 110 further has aCPU 301, a memory 302, a display unit 303, an input/output unit 304, theDSP 305, an antenna 310, a reservation channel modulator 311, atransmission channel modulator 312, a Pilot channel demodulator 313, ananswering channel demodulator 314, a transmission channel demodulator315, a PN code generator 316, a fading-compensating power controller317, an adder 320, multipliers 330 and 331, and a TDD switch 340.

In the mobile terminal 110, as illustrated in FIG. 3, the CPU 301 thatcontrols the operation of the whole terminal is connected to the memory302 that loads a control program, the display unit 303 that displays thecondition of the operation, the input/output unit 304 that makes theinput/output process on the data to transmit or have received, and theDSP 305 that controls the process for communicating with the basestation 100.

The DSP 305 of the mobile terminal 110 includes the up link transmissionpower setter 111, the up link power control information comparator 112,the up link power control information generator 113 and the powercontrol information transmitter 114 as described above.

The DSP 305 is connected via a bus to the reservation channel modulator311, transmission channel modulator 312, pilot channel demodulator 313,answering channel demodulator 314, transmission channel demodulator 315,PN code generator 316, fading-compensating power controller 317, and TDDswitch 340.

The reservation channel modulator 311 modulates the reservation channelthrough which a notice of reservation for a transmission channel is sentto the base station 100, informing the base station of having datapackets to be transmitted through the transmission channel. Thetransmission channel modulator 312 modulates a plurality of transmissionchannels on which data packets are transmitted.

The reservation packets and data packets, which have been modulated bythe reservation channel modulator 311 and transmission channel modulator312, respectively, are supplied through the adder 320, multiplier 330,fading-compensating power controller 317 and TDD switch 340 to theantenna 310, from which those packets are transmitted from the antennato the base station 100.

The pilot channel demodulator 313 demodulates the pilot channel on whicha pilot signal is transmitted. The signal intensity and TDD timing ofthe received and demodulated pilot signal are supplied to the DSP 305.

The answering channel demodulator 314 demodulates the answering channelon which answering packets are transmitted. The transmission channeldemodulator 315 demodulates a plurality of transmission channels onwhich data packets are transmitted.

The PN code generator 316 generates a plurality of PN codes to be usedon each of the pilot channel, reservation channel, answering channel andtransmission channel.

The fading-compensating power controller 317 controls the transmissionpower on the basis of the fading information produced from the DSP 305.

The TDD switch 340 responds to a TDD timing signal produced from the DSP305 to timely switch the up link 121 and down link 122, or to timelychange over from transmission to reception or vice versa.

FIG. 4 is a timing chart schematically showing the data transmission inthe mobile communication system according to this embodiment. Referringto FIG. 4, reference numerals 401-403 represent the reservation packets,411-413 the answering packets, 421-423 the data packets, and 431 and 432the pilot data.

As illustrated in FIG. 4, the data that are transmitted and received inthe mobile communication system contain the reservation packets 401-403,answering packets 411-413, data packets 421-423, and pilot data 431 and432.

That is, when the reservation packets 401-403 are transmitted from themobile terminal 110 to the base station 100, the base station 100 sendsthe answering packets 411-413 to the mobile terminal 110, and then themobile terminal 110 transmits the data packets 421-423 to the basestation 100.

The reservation packets 401-403, answering packets 411-413, data packets421-423 and pilot data 431 and 432 transmitted and received in themobile communication system according to this embodiment are spread intheir spectra in the form of the reservation code, answering code,up/down transmission code and pilot code, respectively, and transmittedon both up link 121 and down link 122 of the same carrier frequency 124.

The channels using the carrier frequency 124 are separated as up link121 and down link 122 in a time sharing manner. Before the mobileterminal 110 transmits data packets 421-423 to the base station, thereservation packets 401-403 are first transmitted on the up link 121from the mobile terminal 110 to the base station 100.

The base station 100 that received the reservation packets 401-403determines a transmission channel to be assigned to the mobile terminal110, and then transmits the answering packets 411-413 on the down link122 to the mobile terminal 110.

The mobile terminal 110 that received the answering packets 411-413transmits the data packets 421-423 to the base station 100.

The pilot signal to be transmitted from the base station 100 to themobile terminal 110 is transmitted only on the down link 122 as thepilot data 431 and 432 are assigned thereto.

FIG. 5 shows the procedure of the process for the transmission powercontrol in the base station 100 of the mobile communication systemaccording to this embodiment.

As illustrated in FIG. 5, the base station 100 makes transmission powercontrol so that the transmission power on the down link 122 isdetermined on the basis of the power control information sent from themobile terminal 110 and the signal intensity on the up link 121, andtransmitted to the mobile terminal 110.

In the base station 100, at step 501, the signal on the reservationchannel or transmission channel is received from the reservation channelmatched filters 214-215 or transmission channel matched filters 216-217.

At step 502, the down link power control information generator 103 ofthe DSP 205 of the base station 100 extracts the intensity from theinput signal on the reservation channel or transmission channel at eachbit.

At step 503, the down link power control information generator 103 ofthe base station 100 estimates the fading of the up link 121 by usingthe power control information of the mobile terminal 110 received by thepower control information receiver 104 and the previously receivedsignal intensity at each bit on the reservation channel or transmissionchannel.

In other words, since the signal on the up link 121 is alreadycompensated for by the mobile terminal 110, the received signalintensity on the reservation channel or transmission channel of the uplink 121 is restored to the previous signal intensity before thecompensation by the mobile terminal 110 by use of the information on thefading within the power control information transmitted from the mobileterminal 110, and then the fading on the up link 121 is estimated.

At step 504, the down link power control information generator 103 ofthe base station 100 computes the transmission power necessary forcompensating for the fading that has been estimated at step 503.

At step 505, the down link power control information comparator 102 ofthe base station 100 compares the necessary power computed by the downlink power control information generator 103 and the maximum permissiblecompensation value of the transmission power which can be compensatedfor by the base station 100.

At step 505, if the transmission power necessary for compensating forthe fading estimated at step 503 is larger than the maximum permissiblecompensation value of the base station 100 as a result of the comparisonbetween the necessary power computed by the down link power controlinformation generator 103 and the maximum permissible compensation valueof the base station 100, the program goes to step 506.

At step 506, the base station 100 stops until the following slot, andthen the program goes back to the step 502.

At step 505, if the transmission power necessary for compensating forthe fading estimated at step 503 is equal to or lower than the maximumpermissible compensation value of the base station 100 as a result ofthe comparison between the necessary power calculated by the down linkpower control information generator 103 and the maximum permissiblecompensation value of the base station 100, the program goes to step507.

At step 507, the down link transmission power setter 101 of the basestation 100 fixes the transmission power on the down link 122 accordingto the necessary power calculated by the down link power controlinformation generator 103.

FIG. 6 shows the procedure of the process for the transmission powercontrol in the mobile terminal 110 of the mobile communication systemaccording to this embodiment.

As illustrated in FIG. 6, the mobile terminal 110 makes transmissionpower control so as to set the transmission power on the up link 121 byreceiving the pilot signal sent from the base station 100, and totransmit to the base station 100 the power control information used tocontrol the transmission power.

In the mobile terminal 110, at step 601, the pilot signal transmittedfrom the base station 100 is received by the pilot channel demodulator313 and fed to the DSP 305.

At step 602, the up link power control information generator 113 of themobile terminal 110 extracts the signal intensity from the receivedpilot signal.

At step 603, the up link power control information generator 113 of themobile terminal 110 integrates the extracted signal intensity over theparticular time slot period in which the received pilot signal istransmitted or over the particular packet period in which the packet issent.

At step 604, the up link power control information generator 113 of themobile terminal 110 computes the attenuation of the pilot signal due tothe distance or the shadowing attenuation of the pilot signal due toobstacles along the channel from the integrated value over the slot orpacket period.

At step 605, the up link power control information generator 113 of themobile terminal 110 computes the compensation value for use in thecompensation for the attenuation calculated at step 604.

At step 606, the up link power control information generator 113 of themobile terminal 110 estimates he fading caused in the pilot signal fromthe signal intensity at each bit of the pilot signal extracted at step602.

At step 607, the up link power control information generator 113 of themobile terminal 110 calculates the compensation value for use incompensating for the fading estimated at step 606.

At step 608, the up link power control information comparator 112 of themobile terminal 110 compares the transmission power necessary tocompensate for the fading calculated by the up link power controlinformation generator 113, and the maximum permissible compensationvalue of the maximum transmission power which can be compensated for bythe mobile terminal 110.

At step 608, if the transmission power necessary to compensate for thefading estimated at step 607 is larger than the maximum permissiblecompensation value of the mobile terminal 100 as a result of thecomparison between the necessary power calculated by the up link powercontrol information generator 113 and the maximum permissiblecompensation value of the mobile terminal 110, the program goes to step609.

At step 609, the mobile terminal 110 stops until the following slot, andthen the program goes back to step 602.

At step 608, if the transmission power necessary to correct the fadingestimated at step 607 is equal to or smaller than the maximumpermissible compensation value of the mobile terminal 100 as a result ofthe comparison between the necessary power calculated by the up linkpower control information generator 113 and the maximum permissiblecompensation value of the mobile terminal 110, the program goes to step610.

At step 610, the up link transmission power setter 111 of the mobileterminal 110 selects a transmission power level nearest to the necessarypower calculated by the up link power control information generator 113from a plurality of previously set transmission power levels.

At step 611, the up link transmission power setter 111 of the mobileterminal 110 sets the transmission power on the up link 121 inaccordance with the compensation value for use in compensating for thedistance or shadowing attenuation which was calculated at step 605 andthe transmission power level selected at step 610.

At step 612, the up link power control information generator 113 of themobile terminal 110 measures the ratio C/I from the integrated valueobtained when the pilot signal was integrated over the slot or packetperiod at step 603.

At step 613, the power control information transmitter 114 of the mobileterminal 110 sends the information of fading set at step 611 and theratio C/I obtained at step 612 as power control information to the basestation 100.

Another embodiment of the mobile communication system using FDD to whichthe invention is applied will be described with reference to FIGS. 7 to9.

Referring to FIG. 7, the FDD mobile communication system includes a basestation 700 which has a down link power control information receiver701, a down link transmission power setter 702, an up link power controlinformation generator 703 and an up link power control informationtransmitter 704, a mobile terminal 710 which has a down link powercontrol information transmitter 711, a down link power controlinformation generator 712, an up link transmission power setter 713 andan up link power control information receiver 714, an up link 721, adown link 722, a guard frequency 723, an up link carrier frequency 724,and a down link carrier frequency 725.

In this system, the base station 700 and the mobile terminal 710 areconnected by the up link 721 for transmitting a signal from the mobileterminal 710 to the base station 700, and the down link 722 fortransmitting a signal from the base station 700 to the mobile terminal710. The up link 721 and down link 722 utilize different carrierfrequencies, or the up link carrier frequency 724 and the down linkcarrier frequency 725, respectively, with the guard frequency band 723provided between the channels in order to prevent the interference.

When the base station 700 sends a pilot signal on the down link 722, themobile terminal 710 receives he pilot signal, and causes the down linkpower control information generator 712 to measure the intensity of thereceived pilot signal on the down link and to thereby estimate theattenuation of the signal and fading condition in the transmission path.Thus, it generates down link power control information for use incontrolling the transmission power in the down link 722.

The down link power control information transmitter 711 of the mobileterminal 710 transmits the generated down link power control informationthrough the up link 721 to the base station 700.

The down link power control information receiver 701 of the base station700 receives the down link power control information sent from themobile terminal 710, and supplies it to the down link transmission powersetter 702. The down link transmission power setter 702 of the basestation 700 sets the transmission power of the down link 722 by usingthe received down link power control information.

The up link power control information generator 703 of the base station700, when receiving the signal on the up link 721 from the mobileterminal 710, measures the condition of fading or the like of the signalon the up link 721, and generates up link power control information foruse in controlling the transmission power of the up link 721. The powercontrol information transmitter 704 of the base station 700 transmitsthe generated up link power control information through the down link722 to the mobile terminal 710.

The up link power control information receiver 714 of the mobileterminal 710 receives the up link power control information sent fromthe base station 700, and supplies it to the up link transmission powersetter 713. The up link transmission power setter 713 sets thetransmission power of the up link 721 by using the received up linkpower control information.

FIG. 8 shows the procedure of the process for the transmission powercontrol in the base station 700 of the mobile communication system.

As illustrated in FIG. 8, the base station 700 makes transmission powercontrol so that the transmission power of the down link 722 is setaccording to the down link power control information sent from themobile terminal 710, and that the condition of the fading or the like onthe up link 721 is measured, thus producing up link power controlinformation, which is transmitted to the mobile terminal 710.

At step 801, the down link power control information receiver 701 of thebase station 700 receives the down link power control information sentfrom the mobile-terminal 710 through the up link 721.

At step 802, the down link transmission power setter 702 of the basestation 700 calculates the necessary transmission power by using thedown link power control information sent from the mobile terminal 710.At step 802A, the down link power control information comparator 706 ofthe base station 700 compares the transmission power necessary for usein compensating for the necessary power that is generated by the downlink power control information generator 705, and the maximumpermissible compensation value of the maximum transmission power thatcan be compensated for in the base station 700.

At step 802A, if the necessary transmission power calculated on thebasis of the down link power control information is larger than themaximum permissible compensation value of the base station 700 as aresult of the comparison, the program goes to step 802B for stopping thetransmission. After the transmission is stopped until the next slot orpacket period, the program goes to step 804, where the signal from thematched filter is received. On the other hand, if the calculatednecessary transmission power is equal to or smaller than the maximumpermissible compensation value of the base station 700, the program goesto step 803, where the transmission power is set.

At step 803, the down link transmission power setter 702 of the basestation 700 sets the transmission power of the down link 722 by usingthe calculated necessary transmission power.

At step 804, the up link power control information generator 703 of thebase station 700 receives the signal sent on the up link 721 from themobile terminal 710.

At step 805, the up link power control information generator 703 of thebase station 700 extracts the signal intensity at each bit from thereceived signal on the up link 721.

At step 806, the up link power control information generator 703 of thebase station 700 estimates the fading of the signal sent on the up link721 from the mobile terminal 710 on the basis of the change of thesignal intensity extracted at each bit, and generates up link powercontrol information.

At step 807, the up link power control information transmitter 704 ofthe base station 700 transmits the up link power control information,which the up link power control information generator 703 has generated,through the down link 722 to the mobile terminal 710.

FIG. 9 shows the procedure of the process for the transmission powercontrol in the mobile terminal 710 of the mobile communication systemaccording to this latter embodiment.

As illustrated in FIG. 9, the mobile terminal 710 makes transmissionpower control so that the transmission power of the up link 721 is setaccording to the up link power control information sent from the basestation 700, and that the condition of the fading or the like of thesignal on the down link 722 is measured, thus generating down link powercontrol information, which is sent to the base station 700.

At step 901, the mobile terminal 710 receives the pilot signal sent onthe down link 722 from the base station 700. At step 902, the up linktransmission power setter 713 of the mobile terminal 710 extracts thesignal intensity at each bit from the received pilot signal.

At step 903, the up link transmission power setter 713 of the mobileterminal 710 integrates the extracted signal intensity over a particulartime, namely, a time slot for which data is transmitted, or a packetperiod for which a packet is transmitted.

At step 904, the up link transmission power setter 713 of the mobileterminal 710 calculates the attenuation of the pilot signal due to thedistance or the shadowing attenuation due to the obstacles along thetransmission path on the basis of the integrated value over the slot orpacket period.

At step 905, the up link power control information receiver 714 of themobile terminal 710 extracts information of the attenuation due to thedistance or shadowing from the received up link power controlinformation.

At step 906, the up link transmission setter 713 of the mobile terminal710 computes a necessary transmission power of the signal to be sent onthe up link 721 on the basis of the attenuation of the pilot signal dueto the distance or the attenuation of the pilot signal due to theobstacles which has been calculated at step 904, and the information ofthe attenuation due to the distance or shadowing which has beenextracted at step 905. At step 906A, the up link power controlinformation comparator 716 of the mobile terminal 710 compares thetransmission power calculated for compensation by the up link powercontrol information generator with the maximum permissible compensationvalue of the maximum transmission power that can be compensated for inthe mobile terminal 710. At step 906A, if the transmission powercalculates at step 906 and necessary to compensate for the attenuationwhich is the result of the steps 904, 905 is larger than the maximumpermissible compensation value of the mobile terminal 710 when thenecessary power calculated by the up link power control informationgenerator 715 is compared with the maximum permissible compensationvalue of the mobile terminal 710, the program goes to step 906B. At step906B, the mobile terminal 710 stops until the next slot or packetperiod, and then the program goes to step 908, where the fading isestimated.

At step 906A, if the necessary power calculated by the up link powercontrol information generator is equal to or smaller than the maximumpermissible compensation value of the mobile terminal 710, the programgoes to step 907, where the transmission power is set.

At step 907, the up link transmission power setter 713 of the mobileterminal 710 sets the above-calculated transmission power of the up link721.

At step 908, the down link power control information generator 712 ofthe mobile terminal 710 estimates the fading in the down link 722 byusing the signal intensity extracted at each bit from the pilot signalat step 902, and the distance or shadowing attenuation calculated atstep 904.

At step 909, the down link power controls information generator 712 ofthe mobile terminal 710 measures the ratio C/I (Carrier/Interference)from the integrated value that was attained by integration over the slotor packet period of the pilot signal at step 903.

At step 910, the down link power control information transmitter 711 ofthe mobile terminal 710 transmits the information of fading estimated atstep 908 and the ratio C/I obtained at step 909 as the down link powercontrol information on the up link 721.

According to the mobile communication system using FDD, as describeabove, the power control information of the up link 721 which has beenobtained in the base station 700 is transmitted to the mobile terminal710 in order for the mobile terminal 710 to control the transmissionpower of the up link 721, and the power control information of the downlink 722 which has been attained in the mobile terminal 710 istransmitted to the base station 700 in order for the base station 700 tocontrol the transmission power of the down link 722.

The maximum permissible compensation value in the above comparingprocess can be dynamically set in accordance with the condition of thecommunication path, for example, the velocity of the mobile terminal.The maximum permissible compensation value further can be set inaccordance with the difference between the data rates of thecommunication packets or the service quality needed. Each of the aboveprocedures for the transmission power control can be implemented by aprocessing software configuration using programs associated with thecontrol procedure.

While the present invention has been specifically described on the basisof the above embodiments, the invention is not limited to the aboveembodiments, but of course, various changes and compensations can bemade on the invention without departing from the scope of the invention.

1. A mobile terminal which communicates with a base station by radio,comprising: an antenna for receiving signals from said base station andtransmitting signals to said base station; and a processor for judgingwhether or not to transmit data to said base station based on acondition of a channel between said mobile terminal and said basestation, wherein, if said processor judges not to transmit said data,said transmission of the data is temporarily stopped.
 2. A mobileterminal according to claim 1, wherein, if said processor judges not totransmit said data, said transmission of the data is stopped for atleast a slot period.
 3. A mobile terminal according to claim 2, whereinsaid condition of a channel includes a signal intensity of a signalreceived via the channel between said mobile terminal and said basestation.
 4. A mobile terminal according to claim 1, wherein saidcondition of a channel includes a signal intensity of a signal receivedvia the channel between said mobile terminal and said base station.